Variation of High-Pressure Torsion Processing Modes for Fabrication of the Hybrid Al–Nb System

In this paper, we study a composite material of the hybrid Al–Nb system fabricated by the method of severe plastic deformation by high-pressure torsion (HPT) up to 30 revolutions. To obtain a composite material, a three-layer Al–Nb–Al stack was subjected to deformation at room temperature on Bridgman anvils under a pressure of 5 GPa at N = 10, 25, and 30 revolutions and a deformation rate of ω = 1 and 2 rpm. The initial diameters of the pure aluminum and niobium disks, as well as the HPT conditions for the formation of monolithic and defect-free composite samples, were selected experimentally. The most intense crushing and mixing of niobium in aluminum occurred at an aluminum disk diameter of 10 mm and deformation conditions of N = 25 and 30 revolutions and ω = 2 rpm. After HPT under optimal conditions, three microstructural zones were observed in the samples: a central zone with wide curved niobium layers in aluminum, a zone in the middle of the radius with a finely dispersed banded structure, and a zone with a uniform distribution of niobium in an aluminum matrix at the periphery of the sample. The HPT was shown to lead to the formation of the Al 3 Nb intermetallic phase. The microhardness along the diameter of the obtained composite samples changed nonmonotonically and depended on the formed structure (microstructural zone).